Jacobsenia kolbei (L.Bolus) L.Bolus & Schwantes

Klak, C., Hanáček, P. & Bruyns, P. V., 2018, A recircumscription of Jacobsenia (Aizoaceae): Re-instating Drosanthemopsis, with two new quartz-endemics from Namaqualand, South Africa and sinking Knersia *, South African Journal of Botany 116 (10), pp. 67-81 : 76

1. Jacobsenia kolbei (L.Bolus) L.Bolus & Schwantes , Kakteen und andere Sukkulenten 5: 69 (1954).

Mesembryanthemum kolbei L.Bolus, Ann. Bolus Herb. 3: 131 (1922). Drosanthemum kolbei (L.Bolus) G.D.Rowley, Natl. Cact. Succ. J. 33(1): 8 (1978).

Type: South Africa, Western Cape, Vanrhynsdorp (3118 BC), Oct. 1917, Kolbe sub NBG 2388/17 ( BOL, holo!) .

Sparsely branched shrubs to 50 cm high, young plants caespitose, adult plants compact with erect shoots with elongated internodes (long shoots) and short lateral shoots with very short internodes; short shoots developing 2 leaf-pairs per season, long shoots developing more leaf-pairs; leaf-pairs often slightly anisophyllous. Leaves often distinctly curved, erect or spreading, mostly terete, 22–60 mm long, 7–10 mm diam., mostly smaller on short shoots; epidermis with large, usually elliptic to polygonal bladder cells. Flowers on erect long shoots only, emerging from the connate portion of the 2nd leaf-pair of the season, 53–60 mm diam., pedicels 25–70 mm long; sepals 5 (rarely 4), spirally arranged; petals white (rarely cerise); filaments white. Fruit shape of capsule seen from above 5-angled, 7–11 mm diam, 5 locules, rarely 6.

Ecology and distribution: The species is found between Vanrhynsdorp and Vredendal in the south northwards to Soebatsfontein in SW Namaqualand ( Fig. 7 ). In shallow rocky soils, usually among other shrubs on outcrops of gneiss of schist. Flowering occurs from July to August.

Diagnostic characters: Jacobsenia kolbei is well characterized by its clump forming habit with erect long flowering shoots. The epidermis of the leaves is covered with large, polygonal cells, with smooth outer walls. The flowers are almost always white (the rare colour of cerise was recorded on the specimen Bean 1281, BOL) and are smaller (53–60 mm diam.) than those of J. hallii (80–85 mm diam.).

Conservation status: The species is known from numerous localities and has been listed as least concern (LC) according to the IUCN criteria (Raimondo, 2009).

Additional specimens examined

South Africa. NORTHERN CAPE: 3017 (Hondeklip Bay): Kookfontein , NNE of Soebatsfontein , sandy flats on the north bank of the Swartlintjies river (-BA), Desmet 339 (NBG) . 3018 (Kamiesberg): farm Boesak (-CB), Bruyns 5370 (BOL) ; 9 km north of Bitterfontein (-CC), Burgoyne 9443 (NBG) ; Bitterfontein, near Rietpoort (-CC), Klak 1891 (BOL) . WESTERN CAPE: 3117 (Lepelfontein): North-east of Brand se Baai , farm Kerskloof (-BB), Klak 2319 (BOL) . 3118 (Vanrhynsdorp): North of Komkans , near Louisfontein (−AA), Klak 2296 (BOL) ; Turn-off from the N7 towards Steenkampskraal, farm Nieuwoudtnota (-AB), Klak 2087 (BOL) ; Nuwerus (-AB), J. Lewis sub NBG2147 /32 (BOL) ; 6 miles south of Nuwerus (-AB), Salter 3833 (BOL) ; near Bitterfontein, koppie (-AB), Peers sub BOL25296 (BOL) ; South of Bitterfontein (-AB), Pillans 6136 (BOL) ; Wolwenes area, Gypsum Mine , west of National Road (-BC), Bean 1281 (BOL) ; Vanrhynsdorp, Zout Rivier (-BC), L. Bolus sub BOL25295 (BOL) ; Koekenaap (-CB), H. Hall s.n. (BOL) ; Vredendal, Holriver (-CB), H. Hall 2867 (NBG) .

Figures

Fig. 7. Distribution of Jacobsenia. J.kolbei and J.hallii, with Knersvlakte phytochorion indicated (red hashes).